I was away reporting most of today, and while I was out, a few federal emails landed in my mail with what probably sounded like a thud. One was an official announcement from the Food and Drug Administration; the others were copies of FDA and NIH emails that people there thought I should see.

They all said the same thing: The six vials of smallpox virus found in an FDA cold-storage room on the National Institutes of Health campus July 1 and announced by the CDC last week had company. A lot of company: 321 other vials. Some of them contained other “select agents,” infectious pathogens considered serious enough — for the illness they create, or the lack of a vaccine to prevent or drugs to treat them — to be considered potential bioterror agents.

Those of us who write about infectious diseases faced a conundrum last week, when the news broke that 60-year-old vials containing viable smallpox virus had been found on the National Institutes of Health campus. A responsible reporter always wants to talk to the experts in any subject. But when it comes to smallpox, experts can be hard to find.

Smallpox was one of the world’s worst killers, from prehistory through the first half of the 20th century. Yet there has not been a case of the dreadful disease anywhere since 1978, so few physicians working today have seen one. The virus is supposed to exist in only two highly secure stockpiles, so few scientists do research on it. And the aggressive campaign that chased the disease from the globe — the only human infection for which that claim can be made — ended 34 years ago. Many of the men and women who led it are in retirement, and a number have died.

Fortunately, the physician who headed that international campaign — 85-year-old Donald Ainslie Henderson, universally known as D.A. — is still working in public health, as a distinguished scholar at the bioterrorism-focused Center for Health Security of the University of Pittsburgh Medical Center. Henderson literally wrote the book on smallpox — twice, in fact: He co-authored the World Health Organization’s definitive 1,500-page reference, Smallpox and its Eradication (known in public health as the Red Book), and in 2009 wrote a personal reminiscence of the global battle, Smallpox: The Death of a Disease. Just last month, he published a lengthy, closely argued essay in the journal he co-edits, Biosecurity and Bioterrorism, urging the WHO to finally consent to destroying the last stocks of smallpox virus. (A decision the international agency declined to take; instead, for the sixth time in a row, it postponed a vote on destruction in favor of more study.) There are only a few people working in public health — not just in the United States, but in the world — who possess equivalent knowledge of smallpox, its eradication, and the persistent fears afterward that it could be used as a bioterror agent.

Last week, I talked to Henderson about the live-virus discovery and whether it will affect calls for all stocks of smallpox to be destroyed. He had some surprising things to say, particularly about the availability of smallpox vaccine. I edited our conversation for clarity and length.

Here’s an update on the vials found on the National Institutes of Health campus last week that were labeled smallpox, and transported earlier this week to the Centers for Disease Control and Prevention: The CDC and NIH have both confirmed that the virus in two of the tubes is viable.

That is, if the vials had broken, and someone had come in contact with the dried contents, the result could have been a smallpox infection — something that has not been seen in the world since 1978.

NIH director Dr. Francis Collins made the announcement in an email sent to staff today, which was shared with me. Simultaneously, CDC director Dr. Thomas Frieden announced in a press briefing that the CDC lab studying the vials, which earlier had identified the contents as smallpox virus based on PCR of the contents’ DNA, had induced growth of the contents in a tissue culture, and confirmed that the growing material is smallpox virus.

Headline-making news today from the Centers for Disease Control and Prevention: Workers clearing out an old storage room on the Bethesda, Md. campus of the National Institutes of Health have found a forgotten box of vials that contain smallpox.

Yes, smallpox. The “most terrible of all the ministers of death,” as Thomas Babington Macaulay called it in his 1848 History of England — a disease that was the world’s most dreadful killer, until it was declared eradicated in 1980. A disease caused by a virus that now is supposed to reside in only two highly secure laboratories on the planet, in Russia, and at the CDC.

Smallpox is the only human disease ever successfully eradicated — pursued to elimination by a relentless dragnet that closed nooses of vaccination around every identified case. After the last natural infection, in Somalia in 1977, the World Health Organization launched a second dragnet, scouring lab freezers and storage rooms for any remaining samples of the virus, and consolidating them in Siberia and Atlanta.

Somehow, these six tubes of freeze-dried virus evaded the search. They were found in the storage room of a lab that now belongs to the Food and Drug Administration but was ceded to that agency by NIH in 1972. They may date back to the 1950s.

A swiftly moving contagious disease threatens children. The government urges parents to vaccinate. But parents are suspicious: They believe the vaccine has unpredictable side-effects and they distrust the government’s motives. When persuasion fails, coercion takes its place. The government demands vaccination — and a showdown looms.

In many aspects, that vignette sounds like today, when pertussis and measles are spreading through unvaccinated children. But what it actually describes is a lost episode of history: not 2010, but 1900, when smallpox spread across the country and life-saving universal — and compulsory — vaccination was imposed on the US population.

In a new book, POX: An American History (The Penguin Press, $27.95) historian Michael Willrich describes what happened next.

I wrote a history of US public health, and so I thought I knew something about vaccines, but I had never heard this story. I asked Willrich, an associate professor at Brandeis University, to answer some questions about it.

Among all the vaccine-preventable diseases, smallpox was uniquely deadly — and so I always assumed there was wide agreement over eliminating it. But POX tells the story of a broad, and surprisingly little-known, resistance movement against smallpox vaccination. Tell us that history briefly. [Read more…]

Here at Casa Superbug, we’re in the midst of moving 1,200 miles, so I’m a little slower reading email than I really ought to be. That’s scant excuse, unfortunately, for not noticing one of the biggest global-health stories in years. Mitigating circumstance: Almost everyone else missed it too.

The news is the effective eradication of rinderpest, a viral disease of cattle. Rinderpest does not infect humans, and even in animals it barely occurs in the Americas (or Australia or New Zealand), though until recently it was common and devastating in Africa, South Asia and the Middle East. So unless you are a large-animal veterinarian or a cattle farmer, the disease might never have been on your radar.

So why care that it is on the verge of being removed from the world? Because this marks the first time that a disease of animals has ever been eradicated — and only the second time that any disease has been eradicated at all. The first was smallpox. That was 30 years ago.

Since then, seven other human diseases have been targeted for eradication: Guinea worm (dranunculiasis), elephantiasis (lymphatic filariasis), measles, mumps, rubella, cysticercosis, and above all polio. None of those eradication programs have yet reached their target. Polio has probably come closest, at the cost of billions of dollars and undoubted millions of hours of volunteer effort — yet each time the goal seems within reach, the disease roars back again.

It has been so long since the eradication of smallpox that — I suspect — we have lost any appreciation for the effort it takes to wipe a disease from the planet. Eradication is hard, hard work. It requires that certain conditions exist, to start with: a robust lab and surveillance infrastructure, an easily-delivered vaccine, an absence of any secondary reservoir that can give the organism a refuge. (Whuch explains why tetanus, living in soil, could never be eradicated.) It takes money, time, extraordinary numbers of people and enormous amounts of political will.

More than anything, perhaps, it requires an up-front acknowledgment of what a difficult task it is going to be. We look back on smallpox, from three decades’ distance, as a historic inevitability — but the smallpox campaign wasn’t the first try at eradicating a disease, only the first successful one. There had been four campaigns before — for malaria and yaws, among others — that failed. Writing almost 20 years after the last case, Dr. DA Henderson, one of the architects of smallpox eradication (and author of the recently published Smallpox: The Death of a Disease) reflected:

…eradication was achieved by only the narrowest of margins. Its progress in many parts of the world and at different times wavered between success and disaster, often only to be decided by quixotic circumstance or extraordinary performances by field staff. Nor was support for the programme generous,whatever the favourable cost-benefit ratios may have been. A number of endemic countries were themselves persuaded only with difficulty to participate in the programme; the industrialized countries were reluctant contributors: and UNICEF… decided that it wanted nothing to do with another eradication programme and stated that it would make no contributions. … Cash donations to WHO during the first 7 years of the smallpox programme, 1967-73, amounted to exactly US $79,500.That is not per year, but the total for that entire period. (Henderson, Bulletin of the World Health Organization, 1996

At a certain point, success begins to breed success; the smallpox campaign succeeded in part because people saw that it was working. But the very last days of the campaign were exhausting. I talked to a number of the smallpox warriors for my first book and heard them describe how, time after time. they thought they were done, only to reach another village and find yet another child with the evil telltale rash. Polio now is caught in the same asymptote: The goal has been so close, for so long, and yet the gap to zero has never quite been closed. With much less fanfare, the rinderpest campaign succeeded.

It is a little shaming to admit that I never noticed how dire a disease rinderpest was, or how robust the campaign against it — which began in 1994 — turned out to be. The United Nation’s Food and Agriculture Organization said last week:

At its height in the 1920s, the rinderpest footprint extended from Scandinavia to the Cape of Good Hope and from the Atlantic shore of Africa to the Philippine archipelago, with one outbreak reported in Brazil and another in Australia. In the early 1980s, the disease was still ravaging livestock herds around the world, with devastating epidemics hitting South Asia, the Middle East and Africa. Losses in Nigeria in the 1980s totalled $2 billion. A 1994 outbreak in northern Pakistan wiped out more than 50 000 cattle and buffalo before being brought under control with help from FAO.

Rinderpest was a lesson in the porousness of borders: It spread around the world, over thousands of years, wherever cattle were herded or traded. (It was in Egypt thousands of years ago, but was probably introduced to sub-Saharan Africa in the late 1800s by cattle bred in India but brought by Italian colonialists.) And it was an illustration of the profound social effects of epidemics: The devastation it caused in Africa, killing 90 percent of the cattle that were the basis of tribal economies, may have paved the way for the takeover and exploitation of traditional African societies by European monarchies.

So hearing the news of the eradication of rinderpest is especially heartening, not just for the animals and livelihoods that will be saved, but also for what it says about the possibility of organizing other eradication efforts for the future. In making the announcement of eradication, the FAO called it “a powerful example of what can be achieved when the international community and individual country’s veterinary services and farming communities cooperate.” That kind of cooperation will be so necessary for future eradication campaigns — not to mention changing antibiotic prescribing patterns to decrease resistance — and it is reassuring to see that, in this case, the collaboration worked so well.